TY - JOUR
T1 - Analysis of free drug fractions by ultrafast affinity extraction
T2 - Interactions of sulfonylurea drugs with normal or glycated human serum albumin
AU - Zheng, Xiwei
AU - Matsuda, Ryan
AU - Hage, David S.
PY - 2014/12/5
Y1 - 2014/12/5
N2 - Ultrafast affinity extraction and a multi-dimensional affinity system were developed for measuring free drug fractions at therapeutic levels. This approach was used to compare the free fractions and global affinity constants of several sulfonylurea drugs in the presence of normal human serum albumin (HSA) or glycated forms of this protein, as are produced during diabetes. Affinity microcolumns containing immobilized HSA were first used to extract the free drug fractions in injected drug/protein mixtures. As the retained drug eluted from the HSA microcolumn, it was passed through a second HSA column for further separation and measurement. Items that were considered during the optimization of this approach included the column sizes and flow rates that were used, and the time at which the second column was placed on-line with the HSA microcolumn. This method required only 1.0. μL of a sample per injection and was able to measure free drug fractions as small as 0.09-2.58% with an absolute precision of ±0.02-0.5%. The results that were obtained indicated that glycation can affect the free fractions of sulfonylurea drugs at typical therapeutic levels and that the size of this effect varies with the level of HSA glycation. Global affinity constants that were estimated from these free drug fractions gave good agreement with those predicted from previous binding studies or determined through a reference method. The same approach could be utilized with other drugs and proteins or modified binding agents of clinical or pharmaceutical interest.
AB - Ultrafast affinity extraction and a multi-dimensional affinity system were developed for measuring free drug fractions at therapeutic levels. This approach was used to compare the free fractions and global affinity constants of several sulfonylurea drugs in the presence of normal human serum albumin (HSA) or glycated forms of this protein, as are produced during diabetes. Affinity microcolumns containing immobilized HSA were first used to extract the free drug fractions in injected drug/protein mixtures. As the retained drug eluted from the HSA microcolumn, it was passed through a second HSA column for further separation and measurement. Items that were considered during the optimization of this approach included the column sizes and flow rates that were used, and the time at which the second column was placed on-line with the HSA microcolumn. This method required only 1.0. μL of a sample per injection and was able to measure free drug fractions as small as 0.09-2.58% with an absolute precision of ±0.02-0.5%. The results that were obtained indicated that glycation can affect the free fractions of sulfonylurea drugs at typical therapeutic levels and that the size of this effect varies with the level of HSA glycation. Global affinity constants that were estimated from these free drug fractions gave good agreement with those predicted from previous binding studies or determined through a reference method. The same approach could be utilized with other drugs and proteins or modified binding agents of clinical or pharmaceutical interest.
KW - Affinity chromatography
KW - Drug-protein binding
KW - Human serum albumin
KW - Protein glycation
KW - Sulfonylurea drugs
KW - Ultrafast affinity extraction
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U2 - 10.1016/j.chroma.2014.10.092
DO - 10.1016/j.chroma.2014.10.092
M3 - Article
C2 - 25456590
AN - SCOPUS:84917738787
VL - 1371
SP - 82
EP - 89
JO - Journal of Chromatography A
JF - Journal of Chromatography A
SN - 0021-9673
ER -